Field of the Invention
The invention relates to a chip module formed of a contact area having a plurality of flat contact elements of electrically conductive material that are insulated from each other. The chip module also has one or more semiconductor circuits electrically connected to the contact elements via connection terminals. The invention also relates to a method of producing such a chip module and also to the use of such chip modules in chip cards or similar data carriers, and also to the use on or in a printed circuit board or on or in a circuit board substrate.
In the production of chip cards, chip modules are produced as technically finished intermediate products and are independently processed further into final products. A chip module is understood here to be a configuration formed of a contact area having a plurality of flat contact elements of electrically conductive material that are insulated from each other. The chip module also has one or more semiconductor circuits electrically connected to the contact elements via connection terminals. The one or more integrated semiconductor circuits are disposed in a substrate in the form of chips which are connected via connection terminals to a system of conductor tracks provided on at least one side of the substrate. In the case of an already known chip module, the substrate is formed by a carrier, produced mainly from epoxy or similar plastics material, on which the actual semiconductor chip is mounted, and on which the usually gold-plated, generally six or eight contact elements are disposed on the outer side of a customary chip card with contacts of the ID-1, ID-00 or ID-000 format, via which an electrical connection to an external reading/writing station for the power supply and the data transmission to the microcontroller circuit integrated in the chip card takes (sic) place.
The position of the contact elements with respect to the chip card body and their size is laid down in International Standard ISO 7810 or ISO 7816-2. For further details and features regarding the structure and the production of a chip module and chip card, reference is hereby made expressly to the authors Wolfgang Rankl and wolfgang Effing, who wrote Handbuch der Chipkarten [Handbook of Chip Cards],Carl Hanser Verlag, 1995, ISBN 3-446-17993-3 and to the full content thereof.
On account of increasing applications relating to security in the field of chip cards, the demand for microcontrollers that meet the highest security requirements is growing. A high security level is made possible by the use of so-called cryptocontrollers, which achieve extraordinary computing performances with regard to the high-speed execution of asymmetric on-chip security algorithms by use of coprocessors. Due to the dual use of cryptocontrollers both in chip cards and on circuit boards, for example in the case of so-called PCMCIA plug-in cards, reading systems at banks and financial institutions for the electrical communication of cryptocontrollers and similar reading units, the different reliability requirements mean that different forms of housings are in use for the cryptocontroller circuits, which however entail considerable disadvantages with regard to costs and logistical expenditures because of the different production processes and the different materials.
Chip housings with surface mounting technology (SMT) capability have specially shaped terminals that permit automatic mounting and a likewise automatic soldering operation. In the case of a preferred connection technique between the semiconductor chip and a circuit board corresponding to the surface mounting technology, a soldering paste is applied to the circuit board via screen printing and subsequently the semiconductor chips, housed as surface-mounted devices, are positioned on it. For establishing the connection between the circuit board and the semiconductor chip, the circuit board is brought into an oven for melting of the solder. In this case, it must be ensured that the soldered connection is reliable and is produced at the defined points, without the solder flowing away, causing short circuits to be created or a poor contact is obtained.
In contrast to this, the currently used chip modules for chip cards have contacts of a relatively large area, which serve primarily for establishing a reliable contact with scanning points of an external reader.
It is thus necessary for different applications to provide different housings or chip carriers, which lead to an increase in production costs on account of different production processes, logistics, materials, etc. German Patent DE-A-44 31 754 C1 discloses a carrier element for incorporation into a chip card with a semiconductor chip disposed on a leadframe conductor carrier and electrically connected with its contact lugs, whereby at least the semiconductor chip and the bonding wires provided for its connection to the contact lugs are surrounded by a plastic compound such that the contact lugs emerge as a conducting connection to the semiconductor chip from the plastic compound. The contact lugs on one of the surfaces of the plastic compound form contact areas, whereby at least two of the contact lugs, in addition to the extension of the contact areas, form terminals for the ends of an antenna coil.
Published European Patent Application EP-A-0 408 904 A2 discloses a surface-mountable component with a power-high-frequency-transistor, which has a plastic form body for encapsulation of each device component, whereby the lower co-planar surfaces of the terminal areas are disposed laterally at the bottom remain free.